The present invention is directed to the field of internal combustion engines and more particularly to a system for and method of feeding gasoline fuel into an engine of this type. More particularly the present invention is directed to that portion of the above-noted field which is concerned with the delivery and metering of a liquid fuel which has been vaporized prior to mixture with intake airstream. More particularly still, the present invention is directed to that portion of the above-noted-field which is concerned with the maintenance of a quantity of vaporized liquid fuel within the P.C.V. vacuum line to assure an adequate supply of vaporized liquid fuel for an otherwise conventional internal combustion engine.